Validation of the Observer-Reported Communication Ability (ORCA) measure for individuals with Rett syndrome.

Abstract

The study goal was to validate the Observer-Reported Communication Ability (ORCA) measure for use with females with Rett Syndrome (RTT). Qualitative interviews, including concept elicitation and cognitive interviewing methods, were conducted with 19 caregivers of individuals with RTT ages 2 and older. A quantitative study was then conducted in 279 caregivers to evaluate construct validity and reliability. After minor modifications were made, the modified ORCA measure was well understood and captured key communication concepts. Quantitative data showed evidence for reliable scores (α=0.90, test-retest intraclass correlation=0.88), minimal floor and no ceiling effects, and strong correlation with the Communication and Symbolic Behaviors Scale (r=0.73). This study provided initial support that the modified ORCA measure is an acceptable caregiver-reported measure of communication ability for females with RTT. Future work should include evaluation of longitudinal validity of the measure and its associations with clinician- and performance-based measures in diverse samples.